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Resultados 1101-1110 de 3,189
The composition of PM1 and PM2.5 samples, metals and their water soluble fractions in the Bologna area (Italy)
2015
Sarti, Elena | Pasti, Luisa | Rossi, Mauro | Ascanelli, Monica | Pagnoni, Antonella | Trombini, Monica | Remelli, Maurizio
In this study the metal composition of PM1 and PM2.5 samples collected in the surroundings of a municipal incinerator located in a suburban–farming area, less than 10 km away from Northeast of Bologna (Italy) was investigated. Seven out of eight monitoring stations were installed in a domain of 8x9 km2 around the incinerator plant; the eighth station was placed inside the urban area of Bologna. The coordinates of four monitoring stations were selected on the basis of a preliminary study by using a dispersion model. Eleven metals (Al, Sb, As, Cd, Fe, Mn, Ni, Pb, Cu, V, Zn) were quantified in both the filter acid–digests and in the water extracts. The PM2.5 collected in all the sites of the domain were highly correlated with exception of the urban site. The daily average metal concentrations in summer were 1.84% and 1.14% for PM2.5 and PM1 respectively, indicating that fine particles are less enriched in metals. Fe, Al and Zn were the most abundant elements, and they represented about the 80% of the total amount of the analyzed ones. The average water soluble metal compositions were 0.71% and 0.41% for PM2.5 and PM1 respectively. In the sites of the suburban–farming studied area the Principal Component Analysis (PCA) and Cluster Analysis revealed differences between water soluble metal compositions in PM1 and PM2.5. The urban sites were characterized by lower total and soluble metals contents than the other PM2.5 stations installed around the incinerator plant. However, no noticeable difference in the concentrations of metals in the particulate matter between the sites chosen as maxima of incinerator emissions and the control sites was observed.
Mostrar más [+] Menos [-]A critical assessment of visual identification of marine microplastic using Raman spectroscopy for analysis improvement
2015
Lenz, Robin | Enders, Kristina | Stedmon, Colin A. | Mackenzie, David M.A. | Nielsen, Torkel Gissel
Identification and characterisation of microplastic (MP) is a necessary step to evaluate their concentrations, chemical composition and interactions with biota. MP ≥10μm diameter filtered from below the sea surface in the European and subtropical North Atlantic were simultaneously identified by visual microscopy and Raman micro-spectroscopy. Visually identified particles below 100μm had a significantly lower percentage confirmed by Raman than larger ones indicating that visual identification alone is inappropriate for studies on small microplastics. Sixty-eight percent of visually counted MP (n=1279) were spectroscopically confirmed being plastic. The percentage varied with type, colour and size of the MP. Fibres had a higher success rate (75%) than particles (64%). We tested Raman micro-spectroscopy applicability for MP identification with respect to varying chemical composition (additives), degradation state and organic matter coating. Partially UV-degraded post-consumer plastics provided identifiable Raman spectra for polymers most common among marine MP, i.e. polyethylene and polypropylene.
Mostrar más [+] Menos [-]Impact of deep-water fish farms on benthic macrofauna communities under different hydrodynamic conditions
2015
Valdemarsen, Thomas | Hansen, Pia Kupka | Ervik, Arne | Bannister, Raymond J.
In this study the environmental impacts of two fish farms located over deep water (180–190m) were compared. MC-Farm was located at a site with slightly higher water currents (mean current speed 3–5cms−1) than LC-farm (<2cms−1). Macrofauna composition, bioirrigation and benthic fluxes (CO2 and NH4+) were quantified at different stages of the production cycle, revealing very different impact of the two farms. Macrofauna abundance and bioirrigation were stimulated compared to a non-impacted reference site at MC-farm, while macrofauna diversity was only moderately reduced. In contrast, macrofauna communities and related parameters were severely impoverished at LC-Farm. This study suggests that deep-water fish farms should not be sited in low current areas (<2cms−1), since this will hamper waste dispersal and aggravate environmental impacts. On the other hand, fish farming at slightly more dynamic sites can lead to stimulated benthic macrofauna communities and only moderate environmental impacts.
Mostrar más [+] Menos [-]Polycyclic aromatic hydrocarbons in surface sediment from Yangpu Bay, China: Distribution, sources and risk assessment
2015
Li, Ping | Diao, Xiaoping | Zhang, Yu | Xie, Yanli | Yang, Fei | Zhou, Hailong | Han, Qian | Wang, Fuqiang | Cheng, Huamin | Wang, Haihua
The study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the surface sediment from eleven sites in Yangpu Bay, China in December 2013 (winter) and July 2014 (summer). The 16 US EPA priority PAHs were found in the range of 1583.2–5701.7ng/g dry weights with an average of 3134.7±1241.3ng/g in winter and ranged from 2161.8 to 4527.2ng/g with an average of 3016.6±748.0ng/g in summer, respectively. The concentrations of the PAHs tended to be relatively high in comparison with other areas from the literatures. The identification using molecular indices analysis indicated that the PAHs originated mainly from pyrogenic and petrogenic sources in most of the sites. According to principle component analysis–multiple linear regression (PCA/MLR) for their source apportionment, the main sources of PAHs were vehicle emissions, petroleum products and biomass combustion. The risk assessment using international sediments quality guidelines and sediments quality criteria indicated that several PAHs, such as Nap, Flu, Phe, Ace, Acy and BghiP in most of the sites would potentially affect organisms in Yangpu Bay.
Mostrar más [+] Menos [-]Ecological risk assessments and context-dependence analysis of heavy metal contamination in the sediments of mangrove swamp in Leizhou Peninsula, China
2015
Liu, Jing | Ma, Keming | Qu, Laiye
Sediments in eight types of mangroves were sampled in the Leizhou Peninsula. Heavy metals were analyzed to investigate the effects on metal distribution of mangrove communities, to evaluate contamination levels, identify sources and relationships between the two. Results showed that mangrove communities have effects on most heavy metal distributions in sediments, especially in the sediment with shrub communities of Aegiceras corniculatum where the contents of many metals are highest. As, Cr and Ni were identified as metal pollutants of primary concern, while Cd was of no concern. Zn, Pb, As mainly originated from anthropogenic source while the other metals are geogenic. Heavy metal distributions were affected by the independent and joint effects of landscape and sediment context; landscape context explains more variations in heavy metals than does sediment physicochemical variables. Total sulfur, total phosphorus and total potassium in sediment, and the existence of paddy field and forest land within 2000m around the sampling sites are significant variables also.
Mostrar más [+] Menos [-]The environment quality of heavy metals in sediments from the central Bohai Sea
2015
Liu, Ming | Zhang, Aibin | Liao, Yongjie | Chen, Bin | Fan, Dejiang
The heavy metals (Cu, Co, Ni, Zn, Cr, Pb, Cd) in surface and core sediments from the central Bohai Sea were analyzed to evaluate the temporal/spatial distribution and pollution status. Cd exhibited gradual increase vertically, while others were stable or declined slightly in core sediments. In surface sediments, metals showed higher values in ‘central mud area of the Bohai Sea’ and the coastal area of the Bohai Bay. Cd and Pb also had high levels in the northeastern part of Bohai Sea. Both the contamination factors (CFs) and the geo-accumulation index (Igeo) indicated that Cu, Co, Ni, and Cr were not at pollution levels, while Pb, Zn, and Cd indicated moderate contamination. Compared with sediment quality guidelines (SQGs), Cu, Zn, Cr, Pb, and Cd were likely to produce occasional adverse biological effects, while Ni showed possible ecotoxicological risks. The combined levels of the metals have a 21% probability of being toxic.
Mostrar más [+] Menos [-]Baseline hydrocarbon levels in New Zealand coastal and marine avifauna
2015
McConnell, H.M. | Gartrell, B.D. | Chilvers, B.L. | Finlayson, S.T. | Bridgen, P.C.E. | Morgan, K.J.
The external effects of oil on wildlife can be obvious and acute. Internal effects are more difficult to detect and can occur without any external signs. To quantify internal effects from oil ingestion by wildlife during an oil spill, baseline levels of ubiquitous hydrocarbon fractions, like polycyclic aromatic hydrocarbons (PAHs), need to be established. With these baseline values the extent of impact from exposure during a spill can be determined. This research represents the first investigation of baseline levels for 22 PAHs in New Zealand coastal and marine avian wildlife. Eighty-five liver samples were tested from 18 species. PAHs were identified in 98% of livers sampled with concentrations ranging from 0 to 1341.6ng/g lipid wt or on wet wt basis, 0 to 29.5ng/g. Overall, concentrations were low relative to other globally reported avian values. PAH concentration variability was linked with species foraging habitat and migratory patterns.
Mostrar más [+] Menos [-]Biodegradation of dispersed Macondo oil in seawater at low temperature and different oil droplet sizes
2015
Brakstad, Odd G. | Nordtug, Trond | Throne-Holst, Mimmi
During the Deepwater Horizon (DWH) accident in 2010 a dispersant (Corexit 9500) was applied at the wellhead to disperse the Macondo oil and reduce the formation of surface slicks. A subsurface plume of small oil droplets was generated near the leaking well at 900–1300m depth. A novel laboratory system was established to investigate biodegradation of small droplet oil dispersions (10μm or 30μm droplet sizes) of the Macondo oil premixed with Corexit 9500, using coastal Norwegian seawater at a temperature similar to the DWH plume (4–5°C). Biotransformation of volatile and semivolatile hydrocarbons and oil compound groups was generally faster in the 10μm than in the 30μm dispersions, showing the importance of oil droplet size for biodegradation. These data therefore indicated that dispersant treatment to reduce the oil droplet size may increase the biodegradation rates of oil compounds in the deepwater oil droplets.
Mostrar más [+] Menos [-]Methods for Treatment of Animal Manures to Reduce Nutrient Pollution Prior to Soil Application
2015
Szogi, Ariel A. | Vanotti, Matias B. | Ro, Kyoung S.
For centuries, animal manures have been a traditional source of nutrients in agriculture. However, disposal of animal manure has become an environmental problem in recent times as a result of increased concentration of animal production within small geographic areas. Manure nitrogen (N) and phosphorus (P) applied in excess of the assimilative soil capacity have the potential to reach and pollute water resources through soil leaching or runoff. Yet, conservation and recovery of N and P is a concern in modern agriculture because of the high cost and future limited supply of commercial fertilizers, particularly P which is extracted from mineral deposits. Therefore, N and P recovery methods are necessary to reduce their excess prior to manure soil application and recover them as valuable products. This article is a review of existing technologies for animal waste treatment and additional new methods for recycling manure N and P and possible recovery as valuable byproducts.
Mostrar más [+] Menos [-]Trace element and stable isotope analysis of fourteen species of marine invertebrates from the Bay of Fundy, Canada
2015
English, Matthew D. | Robertson, Gregory J. | Mallory, Mark L.
The Bay of Fundy, Canada, is a macrotidal bay with a highly productive intertidal zone, hosting a large abundance and diversity of marine invertebrates. We analysed trace element concentrations and stable isotopic values of δ15N and δ13C in 14 species of benthic marine invertebrates from the Bay of Fundy's intertidal zone to investigate bioaccumulation or biodilution of trace elements in the lower level of this marine food web. Barnacles (Balanus balanus) consistently had significantly greater concentrations of trace elements compared to the other species studied, but otherwise we found low concentrations of non-essential trace elements. In the range of trophic levels that we studied, we found limited evidence of bioaccumulation or biodilution of trace elements across species, likely due to the species examined occupying similar trophic levels in different food chains.
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